1. Field of the Invention
The invention relates to electronic screening and, more particularly, to electronic color screening.
2. Prior Art
Screening has long been used in the photographic industry to enable halftone reproduction of continuous tone pictures. In this process, transparent screens having a dot or line pattern formed on them are superimposed on the image to be reproduced and the resultant composite is photographed to form a modified image in which the original image is transformed into patterns of dots or lines of varying density representative of the density of tones in the original. The resultant image can readily be reproduced by conventional mechanical printing processes.
With the increasing availability of low cost computers, the screening function is increasingly performed electronically, that is, in a computer. This allows significant control of many of the factors affecting screening, such as dot density, dot size, screen angle, etc., but electronic screening still remains subject to one of the most significant problems encountered with screening, that is, the formation of Moire patterns. Moire patterns are undesired patterns formed by the interaction of similar patterns that are superimposed on each other. The elimination or minimization of such patterns remains a major goal in screening work.